Hundreds of undeclared savers, some with six-figure sums in their bank accounts, have been caught claiming means-tested state benefits after a significant crackdown.

Almost 1,000 people being paid a range of benefits have been forced to pay back an average of €10,000 each.

One individual claiming the dole had €400,000 in the bank, which he had failed to declare. He was prosecuted and fined €2,500 and got a four-month prison sentence. He had to pay back €30,000 in benefits.

A number of other cases detected will be brought before the courts. Aside from a total €10m repaid in benefits, an estimated €25m was saved for the taxpayer through the payments being cut off.

The Department of Social Protection got information from the Revenue Commissioners on people who are paying DIRT tax. Trawling through its records, the department matched this list with people who were getting means-tested payments, such as Jobseeker's Allowance, One-Family Parent and Disability Allowance.

Typically, the department checked their records where a person was claiming a means-tested payment, but had six-figure amounts in financial savings, which were not disclosed.

The welfare claimants possibly didn't know they were even paying DIRT tax to Revenue – as the tax is deducted at source and paid by the bank to the tax authorities. Banks and other financial institutions have to report interest where the total paid on an account in a year is more than €635.

Revenue gave a selection from this database of names to the department as part of the joint work to tackle the black economy, improve tax compliance and detect welfare fraud.

Social Protection Minister Joan Burton will publish her department's new Compliance and Anti-Fraud Strategy 2014-2018 today, setting out how it intends to combat welfare fraud and abuse in the next few years.

But the plan will also set out anti-fraud crackdowns, such as the 'DIRT project' carried out by the department's Special Investigations Unit working in tandem with Revenue.

FRAUD

A total of 941 investigations have been concluded, resulting in overpayments and disallowance of social welfare payments worth €25.7m. The figure includes the full amount of overpayments, as well as the amount of money that would have been paid out over the course of the year of the claim if the payment had not been stopped.

A department source said the investigation was a "sophisticated operation" and shows the extent to which it now liaises with other agencies of State to tackle welfare fraud and abuse.

"The minister has always championed the welfare system as a safety net for those who need it most, and has gone to great lengths to protect that safety net throughout the economic crisis. However, it's precisely because the State's limited resources should go to those most in need that she makes no apologies for tackling fraud and abuse in the system," the source said.